Catheter lumen partitioner

ABSTRACT

A device and methods for treating an aneurysm includes a catheter capable of insertion into a body to be positioned adjacent the aneurysm, the catheter including a distal end and an operator end opposite the distal end. The catheter forms a circular pathway extending between the distal end and the operator end. A partitioner extends through the pathway of the catheter, the partitioner being rotatable within the catheter and including one or more lumens that provide an orifice from a first end of the partitioner to a second end of the partitioner. The device further includes a first coil extending through the partitioner from the first end to the second end in a first lumen and a second coil extending through the partitioner from the first end to the second end in a second lumen. The first and second lumens may be fully circumscribed by the partitioner and have first and second diameters, respectively.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of copending U.S. patent applicationSer. No. 14/471,289, filed Aug. 28, 2014, which claims the benefit ofpriority under 35 U.S.C. §119(e) to U.S. Provisional Patent ApplicationNo. 61/873,509, filed Sep. 4, 2013. The disclosures set forth in thereferenced applications are incorporated herein by reference in theirentireties.

BACKGROUND

A catheter lumen partitioner and methods for treating aneurysms,traumatic fistulae, and/or tumor embolizations are disclosed. Inparticular, a catheter lumen partitioner may be used in conjunction witha coil delivery system for delivering coils to the location of ananeurysm to be treated.

Devices for delivering and deploying an embolization coil in thetreatment of aneurysms are known in the industry. Occluding devices suchas embolization coils have been used to stop undesired blood flow. Forinstance, introduction of embolization coils in the location of ananeurysm reduces the flow of blood and permits/promotes the naturalclotting-formation process to occur. Such coils may be made of anysuitable material that is compatible with a patient's biology andsuitable to be maintain its structural integrity while in the patient'sbody. Coils for embolization of aneurysms have retained the largestshare of the global neurointervention market that is worth over $1billion annually. Endovascular treatment of aneurysms continues toimprove and the non-invasive nature and rapid procedure recovery hasmade endovascular aneurysm treatment much more popular than surgicalaneurysm treatment.

Aneurysm coiling is not a perfect science, however, as the distributionof coil material within an aneurysm is not uniform. In addition,aneurysm treatment may be limited to the use of only a single coil ifthere is difficulty or safety issues with placing an additional coilwithin the aneurysm after a first coil has been placed. Thus, aneurysmtreatment may not be optimized.

SUMMARY

A new and unique way of partitioning a larger microcatheter is disclosedwherein lumen(s) of the catheter are appropriately sized for coils thatmay be of various sizes. The catheter lumen partitioner may bepositioned inside a catheter prior to insertion of a coil near theaneurysm site, or it may be positioned inside a catheter after thecatheter has already delivered a first coil to near the aneurysm site,in order to deliver a second coil to the aneurysm site. The lumenpartitioner may also be positioned inside a catheter in order to delivertwo or more coils to the aneurysm site at the same time.

In one embodiment, the partitioner may concentrically narrow the lumenof the catheter for receiving, guiding and delivering a smaller coil tothe lesion area. The lumen may include a diameter that is varied in sizein proportion to the catheter and may correspond to the diameter of thesmaller coil being received, guided or delivered. In variousillustrations, the partitioner may extend from the lumen to an interiorsurface of the catheter, or the partitioner may extend through only aportion of the space between the lumen and the interior surface of thecatheter. In still another embodiment, the partitioner adjacent a firstend of the catheter may provide one or more guiding components adjacentthe lumen for placement of a coil into the lumen.

In a second embodiment, the partitioner creates multiple smaller lumensfor simultaneously receiving, guiding and delivering multiple smallercoils to the lesion area. The multiple lumens may be of similar orvaried diameter to each other, and may extend through lumens of similaror varied diameter. The multiple lumens may be eccentrically positionedabout the interior of the catheter.

In a third embodiment, the partitioner is eccentric in the catheter andallows the operator to twist the coil wire and the partitioner usingtorque to adjust the entry position of a coil into the region of ananeurysm or existing coil mass.

Other embodiments of the catheter lumen partitioner are also envisioned.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagrammatic view of customary catheter (black) with acoil (gray) being delivered through a lumen of the microcatheter.

FIG. 2 shows embodiments of a catheter with a single-lumen partitionerand a catheter with a multiple-lumen partitioner, the partitionersextending through the catheters (black) with coil(s) (gray) extendingthrough the partitioners

FIG. 3 shows a diagrammatic cross-sectional view of customary catheter(black) with a coil (gray) being delivered through the lumen of themicrocatheter.

FIGS. 4-7 show various embodiments of a catheter with a single-lumenpartition and a coil extending therethrough.

FIGS. 8-13 show various embodiments of a catheter with a multiple-lumenpartition and multiple coils extending therethrough.

FIG. 14 shows an alternative embodiment of a catheter with amultiple-lumen partition with eccentric or offset lumens and multiplecoils extending therethrough.

FIG. 15 shows diagrammatic examples of 50% packing density of particlesin a two-dimensional aneurysm model, including (A) two particles whosediameters are half that of the aneurysm to achieve 50% packing density,(B) multiple intermediate size particles providing exactly 50% packingdensity, and (C) multiple particles smaller than a red blood cell thatwould unquestionably eliminate blood flow with 50% packing density.

DETAILED DESCRIPTION

Treatment of an aneurysm or similar embolism requires resisting orpreventing the flow of fluid within a relatively confined space. Often,a porous medium may be used to block or prevent such fluid flow.However, resistance to flow of fluid across a porous medium is affectedby several attributes of both the fluid and the porous medium. Incoiling aneurysms, use of coils of different sizes may be the optimalmethod to resist fluid flow in different situations. For instance, acombination of coil sizes may be the most effective way to eliminateflow through an aneurysm. The Kozeny-Carman equation and Darcy's Law inrelationship to aneurysm coiling are described herein.

Based on the equation, larger coils have a significant advantage intheir ability to increase coil packing density and decrease the residualvolume of the aneurysm - thereby decreasing porosity in the equation.Large coils may also be more resistant to compaction within an aneurysm.Smaller coils have the key advantage of decreasing the equivalentchannel diameter when packed at an equal density to larger coils.Smaller coil diameter leads to smaller adjacent channels for flow.Smaller coils also have the advantage of fitting and folding more easilyinto the aneurysm when packing density is already high.

In light of the advantages for larger and smaller coils, an ideal systemfor coiling involves first using large coils to create a sturdy framefor the coil mass and to quickly decrease porosity. Thereafter, smallerand smaller coils may be introduced to maximize packing density(decrease porosity) and to minimize the equivalent channel diameter.

The current disclosure describes a coil delivery device, such as acatheter (10), that could greatly improve the success of coiling totreat aneurysms. Treatment of aneurysms with coils (20) of multiplesizes, instead of the current trend of using coils of very similarsizes, could make such a device invaluable to save time and save moneyin preventing the use of additional microcatheters. Instead, a singlecatheter (10) may be used to deliver multiple coils of varying sizes.

Use of various sizes of coils provides an efficient means to pack orprevent fluid flow near an aneurysm, for example. An article by Chalouhiet al. explored the importance of coil packing density in stent-assistedembolization.1 There is overwhelming evidence that increased coilpacking density improves the probability of aneurysm occlusion, butreliance on this variable in isolation when using multiple types ofcoils may generate misleading results.

Several permutations of the original 0.010 inch diameter Guglielmidetachable coil design have been produced since the original waspresented in 1991.2,3 Among size, shape, stiffness, and lengthmodifications, alteration of coil diameter has become a popular methodfor increasing coil packing density within an aneurysm and presumablyaiding effective aneurysm occlusion. Trufill (0.012 inch, Cordis, MiamiLakes, Fla.), GDC 18 (0.0135-0.015 inch, Stryker, Fremont, Calif.), andPenumbra Coil 400 (0.020 inch, Penumbra, Alameda, Calif.) have been, orare currently, being studied with respect to coil packing density.4-6However, coil packing density may be inadequate for evaluation ofaneurysm treatment when coil diameter varies.

Darcy's law and the Kozeny-Carman equation may be applied to aneurysmcoiling.

Darcy's law, presented by Henry Darcy in 1856, is used to evaluate theflow or pressure drop of a liquid across a uniform, porous medium withknown permeability.⁷ The Kozeny-Carman equation for permeability ofporous media is credited to Josef Kozeny who proposed it in 1927 andCarman who later modified it.^(8,9) When the Kozeny-Carman equation forpermeability is applied, Darcy's law takes the form

$\frac{\Delta \; p}{L} = {\frac{180{\overset{\_}{V}}_{0}\mu}{\Phi_{a}^{2}D_{p}^{2}}\frac{( {1 - ɛ} )^{2}}{ɛ^{3}}}$

where Δp is pressure drop, L is the length of the porous medium, V0 isthe average velocity of fluid at the porous medium cross-section, μ isthe viscosity, ε is the porosity, ΦS is the sphericity of fillingelements which comprise the porous medium, and Dp is the average fillingelement diameter.

Flow through an aneurysm is complex and coil packing within an aneurysmis certainly not uniform, but the principles of Darcy's law and theKozeny-Carman equation apply. Blood viscosity (μ) and velocity at theaneurysm neck (V0) are variables intrinsic to the patient. Length (L) iscomplex in an aneurysm model as the path of bulk blood flow through theaneurysm is tortuous and likely changes through the duration of thepulse. This should be relatively constant when comparing coilingtechniques in identical aneurysms. The sphericity constant (Φs) of acoil is approximated by that of a long cylinder and varies negligiblywith coil diameter. This constant is inversely proportional to surfacearea to volume ratio, so coils with variations that increase surfacearea will decrease Φs, thus increasing pressure drop across the coilmass.

Holding other variables constant, many investigations have convincinglyshown that increasing packing density, which decreases porosity (ε),decreases flow through aneurysms and improves occlusion rates. However,the importance of coil diameter (D) to the filtration/permeabilityequation has been overlooked when comparing coils of different diameterand using packing density to measure results. Particle diameter (Dp) isapproximated by the coil diameter (D), and the Kozeny-Carman equationimplies that pressure drop is inversely proportional to its square.

Simply put, larger coils leave a larger equivalent channel diameter forblood flow between them. Thus, when packing density is constant, coilswith a smaller diameter will be much more effective at stopping flowinto and through the aneurysm. A visual example of extremesdemonstrating this concept is provided in FIG. 15.

Several features of larger coils are still appealing, including betterformation of a coil frame within the aneurysm, resistance to coilcompaction, and faster volume reduction of the aneurysm. Yet, theability to achieve equivalent coil packing density should not be countedamong them. Packing density is an unreliable method of comparing coilsof different diameters. The ideal coil diameter for aneurysmembolization is likely to be situation dependent. Similar to the waybeavers dam a river, optimal embolization may depend on a combination ofcoil sizes. Variability of coil selection likely did not affect theresults provided by Chalouhi et al., and again, this publicationprovides insight into the effect of stents in aneurysm treatment.

Therefore, use of multiple coils having multiple diameters is beneficialin effectively addressing and treating aneurysms. Coil diameters sizesmay be standardized across the industry, while coils of variousdiameters may be combined together to provide an optimal combinationbased on a particular patient's needs.

The current disclosure demonstrates a catheter partitioner (20) thatallows smaller diameter coil(s) (30) to be inserted through amicrocatheter (10) designed for larger diameter coil(s) (30). In such away, coils of multiple diameters may be placed near an aneurysm througha single catheter, reducing the time, resources, and potential issuesassociated with use of multiple catheters to place multiple coils. Thepartitioner (20) may be suspended or exist in irrigation or fluid (notshown) inside the catheter (10) to permit movement or rotation of thepartitioner (20) within the catheter (10). This irrigation may becontinuously around and/or within the partitioner (20). Other forms ofirrigation are widely known in the industry and are also envisioned.

This concept is illustrated in the Figures. FIG. 1 and FIG. 3 show acustomary catheter (10) (black) with a coil (30) (gray) being deliveredthrough the lumen of the catheter. FIG. 2 and FIGS. 4-13 show variouscatheter partitioners (20) extending through the catheter to allowdelivery of one or more coil(s) (30) with varying or smaller diameterswithin the same catheter (10). In illustrative embodiments, thepartitioner (20) may be similar to a second, smaller-diameter catheterthat is insertable into or nests within the catheter (10). In otherillustrative embodiments, the diameter (D) of the coil(s) (30) may beanywhere between 5 mm and 24 mm

In various embodiments, the partitioner (20) may extend from the distalend of the catheter (10) (inside the body) to the operator end of thecatheter (10) so that the operator can push coils through thepartitioner and catheter to the target lesion or aneurysm. Inillustrative embodiments, the coil may be attached to a wire or otherinjection means at the operator end of the catheter, the wire configureto push the coil through the partitioner and out the distal end of thecatheter and may be electronically detached therefrom once the coil isin place. Other methods for pushing the coil through the partitionerand/or detaching the coil from the injection wire or similar means arewell known in the industry.

In other embodiments, the partitioner adjacent the operator end of thecatheter may provide one or more guiding components into the lumen foraligning/inserting a coil within the lumen. The guiding component may bea depression or shaped as a funnel. In other embodiments, thepartitioner may not fully surround the coil within the catheter, asshown in FIG. 8, or the coil may be partially encompassed by an interiorsurface of the catheter. Such a design may provide for a reduction inthe required catheter (10) size and/or in a reduction of the amount ofmaterials required to produce the catheter (10) or partitioner (20).

In illustrative embodiments, FIGS. 4, 5 and 7 show a sheath-likepartitioner (20) that effectively narrows the lumen of the catheter (10)concentrically to provide an appropriate sized lumen for smaller coils(30).

FIG. 6 shows a partitioner (20) that creates an eccentric lumen of thecatheter (10), a feature which could allow the operator to have bettercontrol during coiling with torque of the partitioner/coil pushing wire.Specifically, a coil being ejected from the partitioner may meetresistance at or near the aneurysm location, particularly from otherexisting coils in the area. The coil ejection from the partitioner maybe random in nature and masses already in the area may impede deliveryof the coil. An eccentric lumen permits an operator to turn/twist thepartitioner and coil within the catheter by rotating the partitioner tomove the delivery location of the ejecting coil. Because of theeccentric nature, the coil being delivered may encounter less resistanceafter being moved to a different delivery location.

FIGS. 8-13 demonstrate different embodiments of a multiple-lumenpartitioner (20) in a catheter (10). Such a device would allowsimultaneous introduction of more than one coil (30) through a singlecatheter (10). This could effectively serve the purpose of the “doublecatheter” technique for coiling. It would also allow more efficientcoiling, eliminating some of the time required for removal of coil wiresand insertion of new coils.

FIG. 14 shows another variant where a multiple-lumen partitioner (20 )allows coils (30) of two different sizes to be inserted into a singlecatheter (10) simultaneously and/or eccentrically.

The figures are provided for illustrative purposes and are not intendedto limit the scope of the disclosure.

PUBLICATIONS

The following publications are incorporated by reference to the extentthey relate materials or methods disclosed herein.

-   1. Chalouhi N, Dumont A S, Hasan D, et al. Is Packing Density    Important in Stent-Assisted Coiling? Neurosurgery. 2012. doi:    10.1227/NEU.Ob013e31825c36dd.-   2. Guglielmi G, Vinuela F, Sepetka I, Macellari V. Electrothrombosis    of saccular aneurysms via endovascular approach. Part 1:    Electrochemical basis, technique, and experimental results. J    Neurosurg. 1991; 75:1-7.-   3. Guglielmi G, Vinuela F, Dion J, Duckwiler G. Electrothrombosis of    saccular aneurysms via endovascular approach. Part 2: Preliminary    clinical experience. J Neurosurg. 1991; 75:8-14.-   4. Slob M J, van Rooij W J, Sluzewski M. Coil thickness and packing    of cerebral aneurysms: a comparative study of two types of coils.    AJNR Am J Neuroradiol. 2005; 26:901-903.-   5. Sluzewski M, van Rooij W J. Packing performance of helical    Guglielmi detachable coil (GDC) 18 in intracranial aneurysms: a    comparison with helical GDC 10 coils and complex Trufill/Orbit    coils. AJNR Am J NeuroradioL 2007; 28:1384-1387.-   6. U.S. National Institutes of Health clinical trials registry.    Study of the Penumbra Coil 400 System to Treat Aneurysm (ACE).    http://clinicaltrials.gov/ct2/show/NCT01465841. Oct. 28, 2011.    Accessed May 15, 2012.-   7. Darcy H. Les Fontaines Publiques de la Ville de Dijon. Paris:    Dalmont; 1856.-   8. Kozeny J. Ueber kapillare Leitung des Wassers im Boden.    Sitzungsber Akad Wiss. 1927; 136:271-306.-   9. Carman P C. Fluid flow through granular beds. Transactions,    Institution of Chemical Engineers. 1937; 15:150-166.

1. A device for treating aneurysms comprising: (a) a catheter capable ofinsertion into a body to be positioned adjacent the aneurysm, thecatheter including a distal end, an operator end opposite the distalend, and a circular pathway extending between the distal end and theoperator end; (b) a partitioner extending through the pathway of thecatheter, the partitioner being rotatable within the catheter andincluding two or more lumens, the lumens providing an orifice from afirst end of the partitioner to a second end of the partitioner; (c) afirst coil extending through the partitioner from the first end to thesecond end in a first lumen, the first lumen fully circumscribed by thepartitioner and having a first diameter; and (d) a second coil extendingthrough the partitioner from the first end to the second end in a secondlumen, the second lumen fully circumscribed by the partitioner andhaving a second diameter.
 2. The device of claim 1, wherein the two ormore lumens are concentric around the circular pathway of the catheter.3. The device of claim 1, wherein the two or more lumens are eccentricaround the circular pathway of the catheter.
 4. The device of claim 1,wherein the first coil has a first diameter and the second coil has asecond diameter, and the second diameter of the second coil is less thanthe first diameter of the first coil.
 5. The device of claim 1, whereinthe second diameter of the second lumen is less than the first diameterof the first lumen.
 6. The device of claim 1, wherein the partitionerincludes at least one guiding ramp to assist with insertion of the firstcoil into the first lumen.
 7. A method of treating an aneurysm, themethod comprising placing multiple embolic coils of different diametersadjacent the aneurysm through use of a partitioner within a catheter,wherein the largest diameter coil equals or exceeds twice the diameterof the smallest diameter coil.